Within

chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

for

acid–base reaction An acid–base reaction is a chemical reaction that occurs between an acid and a base. It can be used to determine pH via titration. Several theoretical frameworks provide alternative conceptions of the reaction mechanisms and their applica ...

s, Immobilized pH gradient (IPG)

gel A gel is a semi-solid that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state, although the liquid phase may still dif ...

s are the

acrylamide Acrylamide (or acrylic amide) is an organic compound with the chemical formula CH2=CHC(O)NH2. It is a white odorless solid, soluble in water and several organic solvents. From the chemistry perspective, acrylamide is a vinyl-substituted primary ...

gel matrix co-polymerized with the pH gradient, which result in completely stable gradients except the most alkaline (>12) pH values. The immobilized pH gradient is obtained by the continuous change in the ratio of ''Immobilines''. An ''Immobiline'' is a weak

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

or base defined by its pK value. Immobilized pH gradients (IPG) are made by mixing two kinds of acrylamide mixture, one with Immobiline having acidic buffering property and other with basic buffering property. The concentrations of the buffers in the two solutions define the range and shape of the pH gradient produced. Both solutions contain acrylamide monomers and catalysts. During polymerization, the acrylamide portion of the buffers co polymerize with the acrylamide and bisacrylamide monomers to form a polyacrylamide gel. These polymerised gels are backed with plastic based backing that allow ease in handling and improve IPG's performance. The gel is then washed to remove catalysts and unpolymerized monomers, which interfere with isoelectric separation. IPG increased reproducibility of Isoelectric focusing and 2D-Gel Electrophoresis. Other advantages are increased resolution, reproducible separation of alkaline proteins and increased loading capacity (up to 10 mg). This alternative method eliminates the problems of gradient instability and poor sample loading capacity associated with carrier ampholyte pH gradient.Wilkins et al., Proteome Research: New Frontiers in Functional Genomics. Page 14. Springer, 1997 (Germany) Commercial precast IPG gels are available.

References

Acid–base chemistry